Amazon.com: Nikon 7238 Action Ex Extreme 8 X 40 mm All Terrain Binoculars: Camera & Photo

From the Manufacturer

The Monarch ATB 42mm with Dielectric High-Reflective Multilayer Prism Coating binocular features brighter, sharper colors, crisp and drastically improved low-light performance. A new body style provides unparalleled strength and ruggedness in a package that is comfortable to carry all day. With rugged rubber armor for added durability and a firm grip even in the worst conditions, Nikon guarantees every ATB to be 100% waterproof and fogproof, each is backed by Nikon's 25 Year Limited Warranty and No-Fault Repair/Replacement Policy. The new Monarch ATB 42mm with Dielectric High-Reflective Multilayer Prism Coating binocular is available in 8x42, 10x42 and 12x42. It is also available in Team REALTREE models with the REALTREE APG HD camouflage pattern.

Technical Specs

Model	7x35	8x40	7x50	10x50	12x50	16x50
Magnification x	7	8	7	10	12	16
Objective Diameter	35	40	50	50	50	50
Angular FOV – Real	9.3	8.2	6.4	6.5	5.5	3.5
Angular FOV – Apparent	59.3	59.7	42.7	59.2	59.9	52.1
FOV @ 1000 yds	488	430	335	341	288	183
Close Focus Distance (ft.)	16.4	16.4	23	23	23	23
Exit Pupil (mm)	5	5	7.1	5	4.2	3.1
Relative Brightness	25	25	50.4	25	17.6	9.6
Eye Relief (mm)	17.3	17.2	17.1	17.2	16.1	17.8
Size (L&W) (in)	4.7 x 7.2	5.4 x 7.4	7 x 7.7	7 x 7.7	7 x 7.7	7 x 7.7
Weight (oz)	28.2	30.2	35.3	36	36.9	36.7

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Additional Action EX Highlights:

BaK 4 High Index Roof Prisms
Tripod adaptable
Long eye relief for eyeglass wearers

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Warranty Information

Nikon is dedicated to quality, performance and total customer satisfaction. If your Nikon binocular, Spotting Scope or Fieldscope requires service or repair not covered by our 25 Year Limited Warranty, Nikon will repair or replace it (even it was your fault) for just $10, plus return shipping and handling.
Excludes – StabilEyes, Laser Rangefinders and Spotting Scope/Fieldscope eyepieces.

FAQ's

Real field of view
Real field of view is the angle of the visible field, seen without moving the binoculars, measured from the central point of the objective lens. The larger the value is, the wider the viewfield available. For example, binoculars with a wider field of view are advantageous for locating fast-moving wild birds within the viewfield. This also applies for finding small nebulas or a cluster of stars in astronomical observations.

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Apparent field of view
Apparent field of view is the angle of the magnified field when you look through binoculars.
The larger the apparent field of view is, the wider the field of view you can see even at high magnifications.

With the conventional method used previously, the apparent field of view was calculated by multiplying the real field of view by the binocular magnification. (With this formula, apparent field of view wider than 65˚ is called wide field of view.)

After revision, Nikon's figures are now based on the ISO 14132-1:2002 standard, and obtained by the following formula:

tan ω' = τ x tan ω
Apparent field of view: 2ω'
Real field of view: 2ω
Magnification: τ
(With this formula, apparent field of view wider than 60° is called wide field of view.)

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For example, the apparent field of view of 8x binoculars with an 7.0°real field of view is as follows:
2ω' = 2 x tan^-1(r x tan ω)

= 2 x tan^-1(8 x tan 3.5)
= 52.1°

Relative Brightness
Relative brightness value is obtained by squaring the diameter of the exit pupil. The greater the relative brightness is, the brighter the image will be. With 8x42 binoculars, the brightness is (42÷8)2= 28.1. This means that if the magnification is the same, the larger the effective diameter of the objective lens, the brighter the image will be.

Do binoculars with the same exit pupil offer the same brightness?

No. Brightness may vary even if the exit pupil is the same. This is because the amount of light reaching the viewer's eyes varies according to the number of lens elements and quality of lens/prism coatings. Superior optical design and highquality coating greatly contribute to the brightness of binoculars. Brightness values specified in product brochures, etc. are theoretical ones calculated in the design process. Please note these factors when comparing actual brightness values.

Prisms
Prisms are what let you see a correctly oriented image when you look through a pair of binoculars. There are two types of prisms in common use, Porro prisms and roof prisms.

Roof prisms are essentially in line inside the optical tubes, and make for a more compact set of binoculars. Roof prism binoculars have straight tubes (the front/objective lens is in line with the rear/ocular lens), and are therefore more compact, an important consideration for the sportsman. They usually have two pivot points between the tubes, and are more difficult to adjust to the spacing of your eyes. Roof prisms can give an optical image equal to the best Porro prisms, but for technical reasons they usually do not. To be really good, roof prism binoculars have to be in the high price class. Do not attempt to economize on roof prism binoculars.

Porro prism binoculars can be identified by their offset tubes; the objective lens is not in line with the ocular lens. The front lenses are usually closer together than the rear lenses, but the reverse can also be true, particularly in compact models. The Porro prism design is usually optically superior to the roof prism design, especially in medium priced class binoculars. Porro prism binoculars have a single pivot between the two halves of the binocular, and are therefore easy to adjust for the distance between your eyes.

Like roof prisms, not all Porro prisms are created equal. BAK-4 prisms are the best; they are made of superior optical glass that produces clearer images. These are what you want in your binoculars. BK-7 prisms are also used, usually in lower priced binoculars. These are satisfactory, but they are inferior to the BAK-4 prisms. Some manufacturers will not tell you what kind of prisms they use, usually because they are of inferior quality. BAK-4 prisms show a truer round, which translates to better light transmission and edge-to-edge sharpness

Prism Coatings
Multilayer coating is also applied to prisms to raise transmittance. A roof prism system has one surface that does not feature total internal reflection, so vapor deposition with metals, etc. must be used to raise the reflectivity of this surface. Also, phase-correction coating on roof surface ensures high-contrast images.
*Binoculars' brightness and contrast are affected by not only prism coatings, but also the number of objective lens and eyepiece lens, and types of coatings.

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Metal-vaporized, high-reflectivity prism coating
Using vacuum-vaporization technology, metallic material such as aluminum or silver is applied to the reverse side of a prism surface that is not totally reflective. This raises the reflectivity of the prism mirror surface.

Dielectric high-reflective multilayer prism coating
This coating features reflectance that exceeds 99%. By utilizing light interference, this coating assures high reflectivity across the full visible range, and ensures high color reproducibility.

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Reflectance characteristics of prism coatings on mirror surface
The horizontal axis indicates the wavelength of light. The vertical axis indicates the reflectance of light.
Binoculars' brightness is determined not only by the reflective mirror, but also by the total optical system such as the number of lenses and quality of coatings.

Phase-correction coating

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A roof (Dach) surface can cause phase shift of light that affects image resolution. This phenomenon is caused by phase differences arising from total light reflection on a roof (Dach) surface and it can occur with even a perfectly processed prism. Phase-correction coating is applied to the surface to minimize loss of resolution, ensuring high-contrast images.

Twilight Factor
The factor that has the greatest impact on resolution or image detail, will be dependent upon the amount of light available during the time of observation. During daylight hours, when your eye pupil size will be only about 2 to 3mm, magnification will be the principal factor in image resolution. At night, with the eye pupil dilated to 6 to 8mm, aperture size is the controlling factor. In twilight conditions both of these factors control resolution effectiveness and the twilight factor is the term that compares binocular performance under these conditions.

The twilight factor is calculated by taking the square root of the product of the magnification and the aperture. The higher the twilight factor, the better the resolution of the binocular when observing under dim light conditions. For example, a 10 X 40 (twilight factor 20) would effectively resolve better under these conditions than a 7 X 35 (twilight factor 15.4) even though the 10 X 40 has a smaller exit pupil. Remember, however, that the twilight factor does not take into account the transmittance or quality of the optical system.

Product Description

Key Features:

Aspherical lenses eliminate virtually all distortion
_ Quick, smooth central focusing
_ Tripod adaptable (with Product #7650)
_ Diopter control to regulate vision imbalance
_ BaK4 high index prisms
_ Precision aligned sharp multicoated optics for bright, clear images
_ Standard-size armored bodyThe new Nikon Action Extreme" binoculars feature an all-metal chassis with lens fittings housed in a tough, lightweight polycarbonate body shell. Like all Nikon All Terrain Binoculars, the EX is nitrogen-filled and O-ring sealed for total waterproof, fogproof and shockproof performance in any environment. The binocular bodies are ergonomically shaped, tripod adaptable and are rubber coated for a non-slip grip, whether wet or dry.The new Extreme ATB offerings utilize high-resolution lenses and prism systems crafted from Nikons exclusive Eco Glass", which is made without the use of arsenic or lead. This lens system provides an extremely clear, distortion-free image over the entire field of view. The lens elements each incorporate multi-layered anti-reflective coatings formulated to deliver optimum brightness, high contrast, true color rendition and flare-free viewing in most lighting conditions. The Extreme" series binoculars each feature a unique, click-stop eyecup design that not only delivers long eye relief, but also allows for variable eye relief that is customizable to the users own eyes and eyeglasses. The binoculars are central focus with a diopter control to correct for normal right/left eye vision imbalance.The Extreme ATBs all feature Apparent Angles of view that exceed 65 degrees, making them true Wide Angle binoculars while two of the models, the 7x35 and 8x40, will provide a field of view of over 420 at 1,000 yards, making them true wide field binoculars.

127 of 127 people found the following review helpful:

5.0 out of 5 stars Crazy good for the money, December 6, 2006

P. R. Carter (Raleigh, NC) - See all my reviews
(REAL NAME)

This review is from: Nikon 7238 Action Ex Extreme 8 X 40 mm All Terrain Binoculars (Electronics)

These are for anyone on a budget that wants to upgrade from that old pair of travel binoculars or from Uncle Fred's 1954 hand-me-downs. They are *Waterproof* (very important, it's easy to confuse these with the lower-quality Nikon Action range) and fogproof, with clear and bright images. Very solid feel and compact for a full-size Porro-prism design. The 7x35 version of the Action Extreme won the highest position in the Cornell Ornithology Lab 2005 binocular shootout out of 15 budget entries - probably because the 8x40 was not tested.

Yes, they aren't perfect - higher price will get you sharper optics, lighter weights, and slightly better handling - but at this price the only alternative I could find is the Leupold 6x30 Yosemite for around 25% less - and that model is a 6x magnification.

I'm not sure why, but many sites don't cover the warranty on these. You get excellent support from Nikon USA - a 25-year no-fault warranty with a $10 fix or replace fee for the original owner. Combined with the low price and build quality this could be the last pair of binoculars you will ever need to buy.

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64 of 64 people found the following review helpful:

5.0 out of 5 stars Great for birding, November 17, 2007

Jeff Mohamed (Texas) - See all my reviews

This review is from: Nikon 7238 Action Ex Extreme 8 X 40 mm All Terrain Binoculars (Electronics)

I am a long-time birder and have used several different low- to mid-priced binoculars over the past 15 years. I bought these binoculars a month ago, have taken them out on 8-9 birding trips and and have found them to be excellent in all respects.

The binoculars are sturdy and well-balanced without being unduly heavy. The optics make for a very clear, bright image in all conditions. I particularly like that they have three click-stop adjustments for the length of viewing, making it easy for people wearing glasses to get the right length. I also very much appreciate the close-focus capability: about 9 feet, which is much closer than other pairs I have used and which makes them reasonably good for watching butterflies.

I would recommend these to any birder.

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23 of 23 people found the following review helpful:

5.0 out of 5 stars Super Sharp, Great Priced Binoculars!, October 20, 2007

Wolfman-a-go-go (USA USA USA!) - See all my reviews

This review is from: Nikon 7238 Action Ex Extreme 8 X 40 mm All Terrain Binoculars (Electronics)

I am SO pleased with these binoculars. Great eye-relief for eye-glass wearers. Wide angle is as advertised, no tunnel-vision viewing! Thinking of buying a pair for my father for his cruise. Front lens caps are a problem, but just replace with hinged flip-top protectors like on sniper scopes and you're ready to go! Excellent product!

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